It would help maintenance and consistency to create helpers to factorize this with what **prepare_command_pool_set** does for **hit_set_type**, **hit_set_period** etc. For instance 
<pre>
 bsp->set_fpp(g_conf->osd_tier_default_cache_hit_set_bloom_fpp);
</pre>
should probably replace
<pre>
      bsp->set_fpp(.05);
</pre>